The long-term objective of this study is to create software to continually monitor the digital signals from the mouse and keyboard in order to determine when small, systematic changes in mouse button-click and keystroke durations occur which may be associated with early, underlying changes in the muscle that may be a precursor to cumulative trauma. To achieve study objectives, using 36 subjects and a repeated measures design, the specific aims of this project are to: 1) determine whether keystroke duration systematically changes as the durational exposure to keyboard work increases and whether the temporal changes in keystroke durations parallel objective measures from the muscle, 2) determine whether mouse button-click duration systematically changes as the durational exposure to mouse work increases and whether the temporal changes in mouse button- click durations parallel objective measures from the muscle. If systematic, fatigue-related changes can be detected in the digital signals from the mouse and keyboard, the operator's own computer could monitor and proactively notify the user that they may benefit from a change in activities, mitigating potentially adverse changes in the muscle and thereby potentially reducing the operator's subsequent chances for developing a computer-related musculoskeletal disorder. Relevance to Public Health: This study proposes to develop and evaluate a computer activity monitoring program which will non-invasively and continuously monitor for systematic changes in keyboard and/or mouse button click duration which may be indicative of early and potentially adverse changes in the physiologic state of the muscle. If these systematic, physiologic changes can be detected using the mouse and keyboard, the operator's own computer could monitor and proactively notify the user of these early and potentially adverse changes and thereby potentially reduce the operator's subsequent chances for developing a computer-related musculoskeletal disorder.